For example, in a case where editing is performed so as to extract a predetermined section from a video signal compressed and encoded using the MPEG2 method or the like (hereinafter referred to as an encoded video signal), when extraction is performed in units of a GOP (Group of Pictures), the editing can be performed with a comparatively small amount of computation without decoding the encoded video signal.
When extraction is performed in finer units than units of a GOP, namely, in units of a frame, on the other hand, decoding processing is required due to the presence of a reference relationship between pictures. The simplest method is to extract a predetermined section after decoding all encoded data.
However, even though all encoded data is decoded, re-encoding is necessary after the extraction, resulting in possible extra computation and an increase in the time required to complete the series of processes.
Therefore, a technique called smart rendering editing exists as a method for executing editing as rapidly as possible so as to extract a predetermined section in units of a frame from an encoded video signal (see, for example, Patent Document 1).
In the smart rendering editing, for example, in a case where editing is performed to extract an arbitrary section from a sequential encoded video signal as shown in part A of FIG. 1, only GOPs respectively including a leading end and trailing end of the extracted section are individually decoded to extract desired frames which are re-encoded.
Further, in an intermediate portion other than the GOP at the leading end and the GOP at the trailing end of the extracted section, the encoded video signal is extracted as it is without being decoded.
Therefore, in the encoded video signal corresponding to the extracted section after the smart rendering editing, as shown in part B of FIG. 1, portions subjected to re-encoding (re-encoded portions) and a portion that is sandwiched between the re-encoded portions and that is not subjected to re-encoding (intermediate portion) exist. Note that rewriting of a predetermined parameter within the encoded video signal occurs in both the re-encoded portions and the intermediate portion.
Meanwhile, in the current situation, the MPEG2 method is used as a standard video signal compression-encoding method. In the future, however, the prevalence of the H.264/AVC method, which can provide a higher compression ratio than the MPEG2 method without degrading the image quality, is expected to increase.
In the H.264/AVC method, it is specified that in a case where a predetermined data sequence (0x00, 0x00, 0xXX (where XX is 00, 01, 02, or 03)) as shown in part A of FIG. 2 is included in an encoded string obtained by encoding a video signal, as shown in part B of FIG. 2, 0x03, referred to as an EPB (Emulation Prevention Byte), be inserted between 0x00, 0x00 and 0xXX in order to prevent the pseudo-occurrence of start codes (0x00, 0x00, 0x01) specified in the H.264/AVC method. In an H.264/AVC encoded video signal, therefore, a predetermined data sequence has an EPB inserted therein.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-104361